Thymus hyperplasia after resolution of hypercortisolism in ACTH-dependent Cushing’s syndrome: the importance of thymic vein catheterization

Abstract

Thymic hyperplasia has been described after the resolution of hypercortisolism from several etiologies, causing great diagnostic dilemmas. We describe a case where the catheterization of the thymic vein was essential for the differential diagnosis of a thymic enlargement in an adrenalectomized patient with ACTH-dependent Cushing's syndrome. The patient was a 48-year-old female with clinical and laboratorial data suggesting Cushing's disease. She underwent a transsphenoidal surgery with no tumor visualization and no remission of the syndrome. Histopathological studies disclosed a normal pituitary. She underwent a bilateral adrenalectomy and 8 months later a chest CT showed an increase of left thymic lobe, which was previously non-existent. After a negative 111 In-pentetreotide scintigraphy, the patient underwent simultaneous and bilateral catheterism of the petrosus sinuses and catheterization of the thymic and inominate veins and no ACTH gradient was shown among the sites of collection. She did not undergo thoracotomy and a follow-up was established. During the evolution, there was a spontaneous regression of the thymic lesion 38 months after the diagnosis. The ACTH gradient during the catheterization of thymic vein was essential for the differential diagnosis of the thymic enlargement tumor after hypercortisolism resolution in ACTH-dependent Cushing's syndrome, especially in this case, where the ACTH source was occult, thus avoiding an invasive surgical procedure for a benign entity with spontaneous resolution.European Journal of Endocrinology 154 807-811

Complications of Cushing's syndrome: state of the art

“…Testing patients with Cushing's syndrome for autoimmune thyroiditis and coeliac disease is suggested, particularly during the 6 months after Cushing's syndrome remission. 100 Thymic hyperplasia might develop three or more weeks after remission from Cushing's syndrome, 102 but it may spontaneously regress. The diff erential diagnosis between thymic hyperplasia after control of hyper cortisolism and a thymic source of ectopic ACTH production can be challenging.…”

Carcinoid tumor arising in a thymic bronchogenic cyst associated with thymic follicular hyperplasia

“…Thymic follicular hyperplasia is known to be associated with myasthenia gravis and some autoimmune diseases, 29 but no such manifestation has been seen in our case clinically so far. It has also been associated with multiloculated thymic cysts 30 and after the treatment of a variety of malignant tumors 31 and Cushing syndrome, 32 but to the best of our knowledge, association with either pulmonary or thymic carcinoid tumor has not been reported before.…”

Rebound thymic hyperplasia after adrenalectomy in a patient with Cushing syndrome caused by adrenocortical adenoma

“…[ 17 ] Another case showed spontaneous regression of the thymus 38 months after the initial diagnosis of RTH. [ 18 ] Therefore, the duration of the follow-up for RTH should vary depending on the patient; however, due to its gradual change, at least a 1-year of follow-up is recommended.…”